<?php


namespace App\Http\Controllers\Wechat;


use App\Services\Wechat\ErrorCode;

class WXBizDataCrypt
{
    //
    private $appid;
    private $sessionKey;

    /**
     * WXBizDataCrypt constructor.
     * @param $appid string 小程序appid
     * @param $sessionKey\ string 小程序登录获取会话秘钥
     */
    public function __construct($appid, $sessionKey)
    {
        $this->sessionKey = $sessionKey;
        $this->appid = $appid;
    }

    /**
     * @param $encryptedData string 加密的用户数据
     * @param $iv string 与用户数据一通返回来的初始向量
     * @param $data string 解密后的原文
     * @return int 成功0， 失败返回错误码
     * User: aniu
     * Date: 2020/6/6 6:25 下午
     */
    public function decryptData($encryptedData, $iv, &$data)
    {
        if (strlen($this->sessionKey) !=24){
            return ErrorCode::$IllegalAesKey;
        }
        $aesKey = base64_decode($this->sessionKey);

        if (strlen($iv) != 24) {
            return ErrorCode::$IllegalIv;
        }
        $aesIv = base64_decode($iv);
        $aesCipher = base64_decode($encryptedData);
        $result = openssl_decrypt($aesCipher, 'AES-128-CBC', $aesKey, 1, $aesIv);

        $dataObj = json_decode($result);
        if ($dataObj == NULL){
            return ErrorCode::$IllegalBuffer;
        }
        if ($dataObj->watermark->appid != $this->appid) {
            return ErrorCode::$IllegalBuffer;
        }
        $data= $result;
        return ErrorCode::$OK;
    }
}
